research report

Resiliency Impacts of Plug-in Electric Vehicles in a Smart Grid

Abstract

This project assesses the impact of plug-in electric vehicles (PEVs) on the resiliency of the electricity distribution system by: (1) Assessing the use of PEVs as a resiliency resource during grid outages (Mobility Services+), (2) Assessing and simulating the impact of PEVs on the distribution infrastructure during normal operations, and (3) Determining the local environmental impact of clustering PEVs. A previously developed model of a smart grid consisting of two distribution circuits and a distribution substation was modified to enable the use of PEVs in vehicle-to-home (V2H) and vehicle-to-grid (V2G) configurations. Scenarios were simulated in which PEVs were used to serve critical loads in a home or community shelters, and a model was developed to assess the feasibility of using PEVs in grid restoration, which determined the inrush current of the substation transformer to determine the required power and energy for startup. The use of clustered PEVs and scattered PEVs in grid restoration was also considered. During normal operations, the stress on system components from high PEV demand resulted in accelerated aging and possible failure, thereby negatively impacting distribution infrastructure during normal grid operations. Smart charging is required to retain an acceptable level of resiliency. In contrast, during grid outages, this study demonstrated that PEVs can be used as an environmentally friendly resiliency resource to both serve critical loads and facilitate grid restoration with the qualification that implementation requires system upgrades including smart switches, upgraded inverters, energy management systems, and communication links.

policy brief

Can Plug-in Electric Vehicles in a Smart Grid Improve Resiliency?

Abstract

While the impact of plug-in electric vehicles (PEVs) on electricity generation and transmission has been studied extensively, the impact of PEVs on the resiliency of the local electricity distribution system has not been addressed in detail. Understanding resiliency impacts is important as the increased use of PEVs, and especially the clustering of PEVs in one area (such as a neighborhood), place additional pressures on already aging power grid infrastructure. As an example, charging a large population of PEVs during normal operations can stress system components (such as transformers) resulting in accelerated aging or even failure, which reduces resiliency of the system. On the other hand, PEVs can also increase system resiliency. When connected to the grid, PEVs are an energy resource that can provide electricity for critical services (such as community shelters) during grid outages and facilitate grid restoration by providing electricity to support the restart of transformers and other utility assets.

policy brief

Understanding the Causes and Consequences of Local Growth Control

Abstract

In California, there has been a growing concern about rising housing cost burdens. Declining housing affordability, particularly in job-rich areas, can lead to lengthy commutes and pose significant challenges to achieving sustainable transportation and development patterns. It may also cause disproportionate impacts on vulnerable population groups by pushing members of these group to areas where jobs and other amenities are limited. Although no single factor can fully explain the rise of this critical issue, local growth control measures (e.g., growth moratoriums, density restrictions, and public facilities requirements) and other strict land use regulations have been criticized for constraining the housing supply and adding to jobs-housing imbalances. It is important to understand what motivates local growth control actions, as well as how these controls may affect land use, housing, and transportation.

Phd Dissertation

Physical layer key generation for wireless communication security in automotive cyber-physical systems

Abstract

Modern automotive Cyber-Physical Systems (CPS) are increasingly adopting a variety of wireless communications (Radio Frequency and Visible Light) as a promising solution for challenges such as the wire harnessing problem, collision detection and avoidance, traffic control, and environmental hazards. Regrettably, this new trend results in security challenges that can put the safety and privacy of the automotive CPS and passengers at great risk. Further, automotive wireless communication security is constrained by strict energy and performance limitations of electronic controller units and sensors. As a result, the key generation and management for secure automotive wireless communication is an open research challenge. This thesis aims to help solve these security challenges with a novel key management scheme built upon a physical layer key generation technique that exploits the reciprocity and high spatial and temporal variation properties of the automotive wireless communication channel. A key length optimization algorithm is also developed to help improve performance (in terms of time and energy) for safety-related applications. Channel models, simulations and real-world experiments with vehicles and remote-controlled cars were performed to validate the practicality and effectiveness of the scheme. Lastly, it is shown that generated keys may have high security strength (67% min-entropy for the Radio Frequency domain and high randomness according to NIST tests for the Visible Light domain) and that code size overhead is 20 times less than state-of-the-art security techniques. 

research report

The Causes and Consequences of Local Growth Control: A Transportation Perspective

Abstract

In California, there has been a growing concern about housing unaffordability and its negative consequences, but it has remained unclear how transportation is related to this issue. This report synthesizes the literature on the causes and consequences of local growth control which has been viewed as one of the most significant barriers to expanding housing supply and thus managing travel demand more effectively. Emphasis is on what insights can be gained from the literature and what further research is needed to better understand how transportation influences and is influenced by growth control actions.

policy brief

Will COVID-19 Worsen California’s Truck Driver Shortage?

Abstract

The trucking industry serves as the backbone of the nation’s economy. In 2018, approximately 3.5 million truck drivers were delivering over 70% of all freight tonnage in the United States, generating close to $800 billion in gross revenue annually. While 3.5 million truck drivers represents a significant number of jobs, it is not enough to satisfy demand. The trucking industry suffers from a chronic shortage of drivers. Nearly 70,000 additional heavy-duty tractor-trailer drivers in the United States were needed at the end of 2018, according to the American Trucking Associations. And COVID-19 has brought new challenges that may amplify or dampen the driver shortage and in turn impact supply chains. For example, what if a small percentage of long-haul truck drivers became ill? Would it cripple the industry? Would it significantly delay the delivery of essential medical supplies and equipment? This policy brief summarizes a study from UC Irvine exploring the challenges imposed by COVID-19 on truck drivers, looking at past crises, and interviewing academic and industry experts.

published journal article

Stable Dynamic Pricing Scheme Independent of Lane-choice Models for High-Occupancy Toll Lanes

Abstract

There are two operational objectives for operating high-occupancy toll (HOT) lanes: (i) to maintain the free-flow condition to guarantee the travel time reliability; and (ii) to maximize the HOT lanes’ throughput to minimize the system’s total delay. The traffic dynamics on both HOT and general purpose (GP) lanes are described by point queue models, where the queueing times are determined by the demands and capacities.

This article considers three types of lane-choice models: the multinomial logit model when single-occupancy vehicles (SOVs) share the same value of time, the vehicle-based user equilibrium model when SOVs’ values of time are heterogeneous and follow a distribution, and a general lane-choice model. The article demonstrates that the second objective is approximately equivalent to the social welfare optimization principle for the logit model. Observing that the dynamic price and the excess queueing time on the general purpose lanes are linearly correlated in all the lane-choice models, the article proposes a feedback control method to determine the dynamic prices based on two integral controllers. The article further presents a method to estimate the parameters of a lane-choice model once its type is known. Analytically the article proves that the equilibrium state of the closed-loop system with constant demand patterns is ideal, since the two objectives are achieved in it, and that it is asymptotically stable. With numerical examples, the article verifies the effectiveness of the solution method.

policy brief

A Higher Diesel Tax Increases Road Damage

Abstract

Tractor-trailers dominate the truck cargo industry. Between 1990 and 2010, this industry grew significantly; vehicle miles traveled increased 87 percent and ton-miles increased by 47 percent. While the growth of trucking miles and tonmiles is a positive indicator of economic transformation and expansion, the trucking sector also produces negative externalities, including but not limited to pavement damage. Pavement damage is closely tied to vehicle weight, which is a product of private market decisions driven by the cost of delivery per ton and the frequency of delivery. Understanding the interplay between fuel cost and private sector decisions on truck dispatch (i.e., frequency and load of trucks) is key to understanding infrastructure damage.

research report

A Higher Diesel Tax Increases Road Damage

Abstract

Tractor-trailers dominate the truck cargo industry. Between 1990 and 2010, this industry grew significantly; vehicle miles traveled increased 87 percent and ton-miles increased by 47 percent. While the growth of trucking miles and tonmiles is a positive indicator of economic transformation and expansion, the trucking sector also produces negative externalities, including but not limited to pavement damage. Pavement damage is closely tied to vehicle weight, which is a product of private market decisions driven by the cost of delivery per ton and the frequency of delivery. Understanding the interplay between fuel cost and private sector decisions on truck dispatch (i.e., frequency and load of trucks) is key to understanding infrastructure damage.